Mobile Extraction Array with brine constituent separation, purification and concentration

ABSTRACT

A system that uses single or multiple elements arranged in a single unit or multiple arrays for the extraction, purification, and concentration of lithium and other constituents from a brine that can be constructed in a mobile unit.

Provisional Patent Application 62/577,554 is incorporated in thisapplication in its entirety.

DESCRIPTION OF THE INVENTION

A system that uses single or multiple elements arranged in a single unitor multiple arrays for the extraction, purification, and concentrationof lithium and other constituents from a brine that can be constructedin a mobile unit.

Constituents are targeted by arranging the following unit operationsusing an interdependent multiple array concept: extraction columns,purification membranes, and concentration membranes.

Conventional methods of separating lithium and other constituents frombrines depend upon a specific sequence of variable concentrationstreams. These streams are run through different types of equipment,most commonly packed bed columns. Lithium specifically is selectivelyadsorbed onto the internal packing of the packed bed column. Theinternals, made up primarily of treated material in the form describedbelow is operated using a specific sequence set of steps. The sequenceof flows is required to displace various residual streams minimizingimpurities and maximizing concentration of the targeted constituent forisolation, the conventional system performance is limited by the abilityto increase the concentration of the targeted constituent and decreaseconcentration of the undesired impurities. Conventionally, streamsdilute in the targeted constituent have to be recycled thus creatingspecific sequences and column arrangements that require large volumeinternal components and flow. Large volume internals which may includesorbent particles, sorbent fibers, separation membranes, plates, andother known separation materials must be arranged such that a sharpdistinct difference in the concentration of the stream flowing throughthe equipment containing the internals is present to enable the masstransfer of the targeted constituent to the internals. These internalsare the extracting materials.

An example of the conventional approach is described by the followingsequence. A column of sufficient diameter to support the needed flowrateand of a height with a ratio of diameter to height of 1 to 3 filled witha particle that has been treated to capture and extract a specificconstituent present in the flow is fed brine at an appropriate rate. Thetargeted constituent is held on sites on the extracting material, inthis case, the particle. Saturation occurs once the extracting materialhas reached a point that all available extraction sites have been filledby the targeted constituent. A second stream is flowed through thecolumn to displace the residual liquid from the initial flow. Thislowers the impurities, or the non-targeted constituents. A third flowcomprised of an appropriate constituent concentration removes thetargeted constituent from the extracting material. This is known asproduct flow. The sequence duration and specific makeups of each ofthese streams determine the performance of the column. In many casesstreams of dilute concentration of the targeted constituent are used inthe sequence. This requires the equipment to be large volume, thereforeaffecting the stability of the sharp concentration profile needed todrive mass transfer. There are many other possible sequences includingintermediate arrangements of the columns as well. There are also manyother methods of extracting the targeted constituents including usingthe extraction material sites to grab the unwanted impurities. Othermethods include steps not addressed here which could be wash,breakthrough, backwash, and regeneration.

This invention simplifies the column sequence, reduces the neededvolume, reduces the dynamic shock on the internals, and makes use ofpost column concentration methods not available previously inconventional systems. An embodiment of the invention is described by thefollowing sequence. A stream containing a concentration of lithium oranother targeted constituent is fed into an array of small diametercolumns on the order of one fifth to one twentieth diameter ofconventional columns with a height to diameter ratio in the range of twoto ten. The columns are arranged in a parallel flow array thus allowinga combined feed manifold and a number of parallel single elementsarranged in the array to behave as one flow unit. This enables anextremely sharp concentration profile presented to the extractingmaterial in each of the single elements. This arrangement using singleelements in an array with a distribution manifold acting as one flowunit can be constructed of dimensions that allow its fitting to astandard mobile container. These can be many types. Since manyeconomically recoverable constituents are located at remote sites, theability to bring a mobile system to extract those constituents is noveland useful. Such an array cannot support the complex valving requiredfor conventional sequencing. The number of valves and the complexity ofthe piping would create not only technical barriers due to the hydraulicaction and dynamics that would destroy the internals but it would alsobe economically prohibitive.

In addition to the benefits described above, this invention solvesproblems with the mechanical dynamics that are present in theconventional approach. In the conventional approach, the internals aresubjected to great dynamic movement, vibration and surface to surfaceinteraction. These dynamics grind the internals such that particles orstructures become smaller and smaller. As the packed bed of internalvibrates, the ground smaller pieces fill the previously openinterstitial spaces and the pressure drop increases. A specificapplication of this invention is for lithium. To capture lithium, theinternals must be constructed of size exclusion material, typically oneof many types of alumnosilicates, that has a high surface area and thathas been activated by one of many methods using various chemicals. For alithium example, the activation is completed with a hydroxide and acidsequence to develop the sites for lithium capture, then build astructurally stable particle to make up the internals of the packed bed.The use of these materials is much more susceptible to damage due tohydraulic dynamics as opposed to conventional ion exchange resin whichusually has a more robust structure. This invention solves the problemassociated with the brittle and friable nature of the alumnosilicates inlithium extraction applications. An increased pressure drop reduces theflow that can be obtained trough the system, thus reducing the capacityof the system. The reduced capacity and higher pressure drop leads tomore dynamic action as more flow is attempted to processed through thecolumn thus exacerbating the griding, and exponentially increasing thereduction of the interstitial space. At some point the column isrendered in operable. The invention reduces this dynamic destruction ofthe internals by reducing the stress on the internals and keeping thepressure drop low. The lower pressure drop reduces the grinding andallows much more capacity of the system. This in (urn increases internaluseful life and allows for continued lower cost operation.

The volume of fluid that takes up the space of one column is called abed volume. In column extraction it is helpful to think of the sequencefor loading the targeted constituent on the extraction material sitesand collecting, or stripping, the targeted constituent off theextraction material sites in terms of bed volumes. The extraction arrayin combination with purification and concentration membrane units makesuse of a simplified sequence that maximizes the collected mass of thetarget constituent. At saturation the targeted constituent concentrationon the extraction material is at its peak and the liquid in the columncontains one bed volume of loading, or feed, solution worth ofimpurities.

At saturation in the conventional method the residual impurity liquidbed volume is displaced with a dilute stream and the residual impurityliquid bed volume is sent to spent solution. Next the bed volume ofdilute stream is displaced with a bed volume of clean stream containinga part per million concentration of targeted constituent also known asstrip solution. The same happens in the invention for these twodisplacement step in the sequence. In the conventional method the bedvolume of displaced dilute stream is either recycled or sent to spentsolution so as not to dilute the concentrated target constituent streamthat will be stripped off the sites. In the invention the bed volume ofdisplaced dilute stream can be recycled or pushed forward to thepurification and concentration membrane units because the units canreadily concentrate dilute and clean target constituent streams. In theconventional method the strip solution is pushed for a limited number ofbed volumes to capture a clean and concentrated stream of targetedconstituent. The conventional method does not have the advantage of thepurification and concentration membrane units and has to stop the flowof strip solution when the targeted constituent falls below aconcentration level. The invention allows a greater number of bedvolumes of strip solution to run through the columns resulting in ahigher mass of collected targeted material. This material, known as theproduct cut, will be clean of impurities, but more dilute than theconventional method. The invention's product cut can be more dilutebecause the invention utilizes the purification and concentrationmembrane units. Additionally, in the invention the extraction materialsites in the column are more available than the conventional methodbecause more of the targeted constituent was released, or stripped, fromthe extraction material sites. The next step of the sequence is torepeat the load step pushing the impurity and constituent laden feedsolution back into the column. Because the invention can remove more ofthe targeted constituent, resulting in a greater number of availableextraction material site, a greater number of bed volumes can be loadedback onto the columns than in the conventional system. The invention canoperate without the need for recirculating loads. This results in asimple time based sequence without complex valving conventionallyrequired for high purity product cuts.

As mentioned, the invention product cut is dilute compared toconventional methods. To overcome this challenge a concentrationmembrane is used to remove the solvent, in most cases water, from thestream containing the desired constituent. Concentration membranes aresusceptible to impurity materials affecting the performance of theseparation. This challenge is overcome by using a purification membraneprior to the concentration membrane. In a typical embodiment, a crossflow membrane. Cross flow meaning the way the liquid is presented to themembrane. The cross flow membrane allows the targeted constituent andsolvent to pass, or permeate, as it rejects the undesired impurities. Anexample would be lithium in a chloride brine as the targeted constituentand solvent with divalent cations, most commonly calcium and magnesium,being rejected. Other constituent combinations exist. Purificationmembranes typically reduce the levels of impurities to the parts permillion level. Purification membranes typically are operated at apressure between 100 and 400 psig.

To complete this invention's purification and concentration of thetargeted constituent the product stream that passed through thepurification membrane is now fed into a system containing aconcentration membrane. In this unit the solvent, most commonly water,passes through the membrane and the targeted constituent is rejected,thus concentrates in the reject stream from the concentrating membraneunit. An embodiment of this concentrating membrane is reverse osmosis.Concentration membranes operated as reverse osmosis systems typicallyconcentrate the targeted constituent to weight percentage levels.Concentration membranes operated as reverse osmosis systems are limitedby the osmotic pressure of the solution and the practical limits of thepressure ratings of the single element components. Concentrationmembranes typically operate between 200 and 1200 psig.

Both the purification membrane units and the concentration membraneunits are made up of single elements arranged in arrays. Similar to theextraction array, purification and concentration membrane units can bearranged in arrays and fitted to mobile systems. This allows the mobiledeployment of these unit operations for recovery of targetedconstituents.

The mobile configuration of RO units and ion exchange units is not new,however, the arrangement of selective absorbent, which is a particlewhich is described as one of the possible internals above, in a mobileconfiguration is new and novel and previously unavailable in a smallsingle element configuration due to the previous limitation of themanagement of the dilute streams and the recirculating loads. Theconventional lithium extraction system columns are very large diameterand very large heights. This invention, and its use of the postextraction membrane purification and concentration methods enables theunique and novel use of this configuration to deliver the benefits ofthe invention.

The invention can include the collection of the purified andconcentrated lithium rich brine for use in post extraction productconversion systems. These systems benefit from the purity of the lithiumrich brine and the ability to avoid further raw purification processesto prepare the brine for unit operations including electrolysis,splitting and recovery.

The invention makes use of membrane technology to also isolate CO2 froma feed gas stream which could be simply air, ore as complex as adischarge from a power plant. The CO2 is used to produce the finalLi2CO3 product by reacting the lithium rich brine stream with theseparated CO2. In the case of LiOH production, the raw purification andconcentration system allows the direct feed to a lithium hydroxideelectrolysis system. The purified product will meet the raw purificationrequirements and the system will only require the secondary purificationsystem to prepare the brine for electrolysis to LiOH. In both theseproduct cases, lithium is the targeted constituent, but other elementsmay behave in a similar fashion using the same scheme.

1. A system of single elements arranged in an array for the extraction,isolation, purification, and concentration of lithium and various otherconstituents.
 2. The combination of the single element array of claim 1with the use of a purification membrane similarly arranged in arrays forthe purification of lithium and various other constituents.
 3. Incombination with the array of claim 1 and the purification array ofclaim 2 a concentration array enables greater capacity and reduceddestruction of the extraction material.
 4. Targeted constituents ofclaim 1, 2, or 3 can include but are not limited specifically to lithiumand could also include: monovalent, divalent, metal, and organicelements. Examples may include calcium, zinc, and carbon.
 5. A system asdescribed in claim 1, 2, or 3 that is able td be fitted to a mobilecarrier. Such examples include but are not limited to an over the roadtrailer, shipping container, railcar, airlift container.
 6. The use ofmembrane separated CO2 to directly produce a lithium carbonate productwhere lithium is the specific targeted constituent for extraction, froma source
 7. The use of electrolysis to directly convert the lithium richbrine to a lithium hydroxide produce with only the requirement of thesecondary purification process having the primary purification processbe the incorporate purification and concentration units described.